﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security;
using System.Security.Cryptography;
using System.IO;

namespace Utility
{
    public class DesHelper
    {
        #region 变量定义
        /// <summary>
        /// 默认密匙 
        /// </summary>
        private string CodeKey = "ChangHong";

        //默认密钥向量 
        private byte[] Keys = { 0xEF, 0xAB, 0x56, 0x78, 0x90, 0x34, 0xCD, 0x12 };
        #endregion

        #region DES加密解密
        /// <summary> 
        /// DES加密 
        /// </summary> 
        public string EncryptDES(string encryptString)
        {
            return EncryptDES(encryptString, CodeKey);
        }

        /// <summary> 
        /// DES解密 
        /// </summary> 
        public string DecryptDES(string decryptString)
        {
            return DecryptDES(decryptString, CodeKey);
        }
        #endregion

        #region DES加密
        /// <summary> 
        /// DES加密 
        /// </summary> 
        /// <param name="encryptString">待加密的字符串</param> 
        /// <param name="encryptKey">加密密钥,要求为8位</param> 
        /// <returns>加密成功返回加密后的字符串，失败返回源串</returns> 
        public string EncryptDES(string encryptString, string encryptKey)
        {
            try
            {
                byte[] rgbKey = Encoding.UTF8.GetBytes(encryptKey.Substring(0, 8));

                byte[] rgbIV = Keys;

                byte[] inputByteArray = Encoding.UTF8.GetBytes(encryptString);

                DESCryptoServiceProvider dCSP = new DESCryptoServiceProvider();

                MemoryStream mStream = new MemoryStream();

                CryptoStream cStream = new CryptoStream(mStream, dCSP.CreateEncryptor(rgbKey, rgbIV), CryptoStreamMode.Write);

                cStream.Write(inputByteArray, 0, inputByteArray.Length);

                cStream.FlushFinalBlock();

                string str = Convert.ToBase64String(mStream.ToArray());

                return str;
            }
            catch
            {
                return encryptString;
            }
        }
        #endregion

        #region DES解密
        /// <summary> 
        /// DES解密 
        /// </summary> 
        /// <param name="decryptString">待解密的字符串</param> 
        /// <param name="decryptKey">解密密钥,要求为8位,和加密密钥相同</param> 
        /// <returns>解密成功返回解密后的字符串，失败返源串</returns> 
        public string DecryptDES(string decryptString, string decryptKey)
        {
            try
            {
                byte[] rgbKey = Encoding.UTF8.GetBytes(decryptKey.Substring(0, 8));

                byte[] rgbIV = Keys;

                byte[] inputByteArray = Convert.FromBase64String(decryptString);

                DESCryptoServiceProvider DCSP = new DESCryptoServiceProvider();

                MemoryStream mStream = new MemoryStream();

                CryptoStream cStream = new CryptoStream(mStream, DCSP.CreateDecryptor(rgbKey, rgbIV), CryptoStreamMode.Write);

                cStream.Write(inputByteArray, 0, inputByteArray.Length);

                cStream.FlushFinalBlock();

                return Encoding.UTF8.GetString(mStream.ToArray());
            }
            catch
            {
                return decryptString;
            }
        }
        #endregion

    }
}
